CSA S478 Guideline on Durability in Buildings David Kayll, FMA, P.Eng. Principal, Building Science Specialist MORRISON HERSHFIELD, Ottawa May 8, 2014

The Durability Process

Take a deep breath…

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1 What Determines Durability?

Durability is not a material property

Durability is a function of a material and its environment

Durability is also a function of installation, future maintenance and replacements

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Durability

1 Service Environment

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Durability

Location & Exposure

Interior Loads

1 Required function(s) of:

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Durability

That depends on whether we are manufacturing open web joists or underwear.” Ted Kesik

Buildings: Institutional, Industrial, Commercial, Residential…

Materials:

“What’s better – steel or cotton?

Durable requires the Team to perform their roles and responsibilities from Conception to Occupancy.

Roles & Responsibilities

The Roles need to be clearly defined for each of the following:

Owner(s) Architect Durability Specialist Building Envelop Consultant Structural Consultant Other Consultants General Contractor Sub-Contractors Manufacturers

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A Durability Plan

Creating a Durability Plan

1 The CSA S478 guideline provides: Set of recommendations to assist designers

Framework for durability targets

Generic advice

Model documents

Appendix with expanded discussions

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A Durability Plan

Tables, Design review, Field review

Sample MH Durability Plan

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A Durability Plan

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Service Life

Service Life: “The actual time during which the

building or any of its components performs without unforeseen costs or disruption for maintenance and repair.” (CSA S478)

Design Service Life (DSL) vs. Predicted Service Life (PSL)

Components will last for 10, 20, 30, 50, 100+ years?

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Predicted Service Life

Historical Materials – We know these ones…

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Predicted Service Life

Innovative Materials – Do we know these ones…???

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Agents of Destruction

Agent Type

Moisture Solid (ice, snow) Liquid (rain, condensation) Gas (water vapour, humidity)

Air Constituents O2, CO2

Air Contaminants Oxides, particulates, sea spray

Ground constituents Sulphates and other salts, acids (from decomposition of organic matter)

Ground contaminants Chemicals from spills and leaks, chlorides from road salt, induced electrical currents

Biological agents Microorganisms, insects, other animals, plants

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Agents of Destruction

Agent Type

Temperature Fluctuations

Solar radiation UV (ultraviolet radiation)

Incompatible chemicals

Corrosion

Differential movements

Between components (shrinkage and swelling), within massive materials (temperature gradient response), creep/flow

Use or exposure

Loading, abrasion, overloading

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How To Predict Service Life?

How do we predict the service life of a material or assembly?

PSL of components within assembly (shortest outside, longest inside)

Use many methods in parallel

Some components will be less

Some components will be more

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How To Predict Service Life?

ISO 15686-1 Factor Method: ESL = RSL x A x B x C x D x E x F x G

A. Quality of components as supplied to the project

B. Design level of a component (e.g. how protected it is from elements which may degrade it)

C. Work execution level or skill level of the installers

D. Indoor environment (e.g. where the component will be utilized)

E. Outdoor environment (e.g. northern climate, coastal climate, southern climate)

F. In-use conditions (refers to specific use conditions of the building)

G. Maintenance level (what is the level of maintenance possible, and likely, for the particular component for the span of its useful life?)

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CSA S478 Method Engineering judgment

Historical performance

Chemical evaluation

Modeling

Performance testing

Manufacturer’s estimates

Plus:

− Environmental conditions − Installation − Operating & Maintenance procedures

How To Predict Service Life?

1 Owner’s expectation of Design Service Life

Ownership type

Building use (present and future)

Future land development

Adaptability

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A Durability Plan

How do you determine a building’s Design Service Life?

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A Durability Plan

Category DSL Examples

Temporary Up to 10 years * Non-permanent construction buildings (sales offices, bunkhouses) * Temporary exhibition buildings

Medium Life 25 to 49 years * Most industrial buildings * Most parking structures

Long Life

50 to 99 years

* Most residential, commercial and office buildings * Health and education buildings * Parking structures below buildings designed for long life category

Permanent 100 years minimum

* Monumental buildings * Heritage buildings

Design and construct with the intent that: Predicted Service Life ≥ Design Service Life

Table 2 in CSA S478

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A Durability Plan

Category DSL Examples

Temporary Up to 10 years * Non-permanent construction buildings (sales offices, bunkhouses) * Temporary exhibition buildings

Medium Life 25 to 49 years * Most industrial buildings * Most parking structures

Long Life

50 to 99 years

* Most residential, commercial and office buildings * Health and education buildings * Parking structures below buildings designed for long life category

Permanent 100 years minimum

* Monumental buildings * Heritage buildings

Design and construct with the intent that: Predicted Service Life ≥ Design Service Life

Table 2 in CSA S478

1 Component DSL in accordance with Table 3 in CSA S478:

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Service Life

Category Effects of failure Example

1 No exceptional problems Replacement of light fittings

2 Security compromised Broken door latch

3 Interruption of building use Repair requires discontinuation of service

4 Costly because repeated Window hardware replacement

5 Costly repair Extensive replacement/ scaffolding needed

6 Danger to health or ecological system Mold, dampness, asbestos

7 Risk of injury Loose handrail

8 Danger to life Collapse of structure

Components in Categories 6, 7 and 8 – Design to last the life of the building

Components in Categories 4 and 5 – Design to last at least half the life of the building

1 Where:

Component(s)/Assembly DSL < Building DSL

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A Durability Plan

What is “…readily replaced…”?

- Design and construct those component(s) and assemblies so that they can be readily replaced.

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A Durability Plan

DSL1

DSL3

DSL5

DSL4

DSL2

DSL6

General Rule: Shorter PSL outboard of longer PSL

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A Durability Plan

Concept Design Review

Review against the Owners Project Requirements

By someone not directly involved in the main design functions.

Could be separate specialist

Document that Concept Design Review was completed

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A Durability Plan

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A Durability Plan

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A Durability Plan

Design Review Sufficient Building Envelope reviews are

required to demonstrate compliance with good practice.

Reviews include managing: − Air leakage − Vapour diffusion − Heat transfer − Water penetration

Method may include: − Marked-up drawings − Letter report(s) − Meeting minutes

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A Durability Plan

Maintenance Requirements Maintenance Requirements & expectations developed during design:

Appropriate material selection (component by component)

Frequency & Access of Maintenance/Repair (future costs); Initial Cost vs. LCC

Risks associated with poor maintenance – Condos vs. Owner occupied

Document Owner acceptance of unusual decisions

Vs.

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A Durability Plan

Maintenance Requirements

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A Durability Plan

Commissioning the Building Envelope BECx activities should be incorporated into specifications. These may include:

Testing requirements (manufacturer or on-site)

Shop drawing submittals

Material submittals

Material Compatibility Testing

Mock-ups

Manufacturer’s field reviews

Sample removals/renewals

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A Durability Plan

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A Durability Plan

Quality Assurance makes sure you are doing the right things, the right way. Quality Control makes sure the results of what you've done are what you expected.

Quality Management

Whose job is Quality?

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A Durability Plan

Key for all projects: Sub-contractor’s workmanship & quality control

Potential transition issues

The contractor’s Quality Assurance activities

The Architect’s or BEP’s Quality Review activities

The expected quality of installation (assists in finalizing the PSLs)

The roles and responsibilities of all team members

Mock-ups

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A Durability Plan

To assess installation quality control,

Address “one-off” details

Quality assurance activities are documented.

A final review is required to confirm compliance with the Project Documents.

Frequency is dependent on team make-up and requirements

Periodic Site Review

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A Durability Plan

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A Durability Plan

The Durability Plan must be endorsed by the Owner (critical step)

The Contractor must state that the building was constructed in general conformance with the Project documents.

Final Sign-off

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A Durability Plan

Appendices and Tables

QUESTIONS?

1 Durable (synonyms):

Long-lasting, hard-wearing, heavy-duty, tough, resistant, strong, sturdy, stout, sound, substantial, imperishable, indestructible, made to last, …

Durability (from CSA S478):

“The ability of a building or any of its components to perform its required functions in its service environment over a period of time without unforeseen cost for maintenance or repair.”

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Durable vs. Durability

SO WHAT?

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Building Life vs. Component Life

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Durability

Roles & Responsibilities

Roles & Responsibilities

Role Responsibility

Owner(s) Establish Building DSL

Architect Establish preliminary assembly DSL

Durability Specialist Consult on appropriate DSL + PSL

Bldg. Env. Consultant Consult on regional risks and agents

Structural Consultant Consult on regional loads

Other Consultants Roofing, leak detection, testing,…

General Contractor Establish QC plan

Sub-Contractors Consult on constructability / establish QA

Manufacturers Consult on PSL

1 Common Issues: Design service lives for buildings and materials rarely

considered, especially at the start

Applicable building industry knowledge is often there…

… but how to use it not known.

Roles and responsibilities not well understood

Understanding of how to document the information not known

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Predicting Service Life

In the design phase, DSL goes from generic to specific: Generic Assembly Specific Assembly

Example:

Composite Panel ABC Alum-Composite Panel (DSL 60+) (DSL 45 years) 50 mm Z-girt (90 Gauge) (DSL 30) 50 mm rigid insulation type IV (DSL 60+) ABC a/v/m barrier (DSL 40) ABC sheathing w/ xxx screws (DSL 50) etc…